troll

troll /v.,n./ [From the Usenet group
alt.folklore.urban] To utter a posting on Usenet
designed to attract predictable responses or flames. Derives
from the phrase "trolling for newbies" which in turn comes
from mainstream "trolling", a style of fishing in which one
trails bait through a likely spot hoping for a bite. The
well-constructed troll is a post that induces lots of newbies and
flamers to make themselves look even more clueless than they
already do, while subtly conveying to the more savvy and
experienced that it is in fact a deliberate troll. If you don't
fall for the joke, you get to be in on it.

Some people claim that the troll is properly a narrower category
than flame bait, that a troll is categorized by containing
some assertion that is wrong but not overtly controversial.